As a new throttling element, an electronic expansion valve has been widely used in the field of household air conditioners. The electronic expansion valve may flexibly change the flow of refrigerant in an air-conditioning system according to requirement of the system, to effectively control the degree of superheat, thereby improving the system efficiency. The electronic expansion valve is a mechanism in which a valve needle is driven to move by a step motor, and an opening of the valve needle is controlled to adjust the size of a valve port, thus adjusting the flow of the refrigerant.
In the household air-conditioning system, a controller provides a voltage pulse sequence to a coil of the step motor in the electronic expansion valve regularly, such that the coil of each phase of the step motor is energized or de-energized according to a certain rule, to regularly control the change of the magnetism of each claw pole of a stator of the coil, and further control the rotation of a rotor, and the rotation of the rotor drives the valve needle to move upward and downward, to achieve the purpose of regulating the flow rate. In an immobile air conditioning system such as the household air-conditioning system, the air-conditioning system is located in a relatively stable environment, and the electronic expansion valve performs flow regulation at a constant speed.
In a mobile air-conditioning system, such as a vehicle air-conditioning system, or other refrigerant circulation systems, the system is located in a complicated and changeable environment, thus the system is required to cope with the effects on the system caused by the change of the environment with a smarter and more flexible manner.